Counterbore



Nov. 17, 1925- 1,561,463 A. c. DE ROCHEMONT COUNTERBORE Filed. March 18, 1924 Patented Nov. 17, 1925.

UNITED STATES ALLEN 0. DE BOCI-IEMQNT, or roars vxourn, NEW newsman.

GQ'UNTERBORE.

Applicationfiled March 18, 1924. SerialNol 699,988;

To all whom it may concern:

Be it known thatI, ALLEN C. DE ROCHE: MONT, a citizen of the United States,residing' at Portsmouth, in the county of Rock in'gham and Stateof New Hampshire, have invented new and useful Improvementsin Counterbores, of which the] following is a specification.

As heretofore constructed counterbores have commonly'been provided with integral pilot 'members for engaging within holes formed of the proper'size to receive them beyond thedesired ,counte'rbored portionof the work to insure that the counterbored portions shall be coaxial With the remainder of the holes. Sincethe cutting edgesofthe tool are on its end inwardly of the pilot it has been customary to notch out the pilot adjacent the cutting edges so that the sharpening tool may traverse the full lengths of these cutting edges: This not only weakens the pilot, but as the tool is ground this notch is almost'certain to. be made deeper by the grinding tool, thus further weakening the tool so that breakage may result. The portion of the pilot thus notched also becomes less accurate guiding element as the cutting edges are ground back. For these reasons such tools have usually been rendered useless after comparatively .little stock has been removedby sharpening. Each of these tools, also, is limited to a single size of hole and counterbore since the pilot is integral. withv the cutting portion.

This invention provides aconstruction wherein the objections abovenoted are eliminated, the pilot beinga separate piece from the cutting portion and removable therefrom. Thus the pilot may be removed when the cutting edges of the counterbore portion are to ee-sharpened thus exposing the entire length of each cutting edge to the grinding operation and obviating injury to the pilot.

With this construction, also, pilots of various diameters may be assembled with counterbores of various diameters, thus obtaining a large number of proportions of counterbore to hole diameterwith a comparatively small number oftool parts. The pilots may also be adjusted relative to the cuttingportion to suit various conditions met with in practice, and if desired, they may be formed as workin tools to perform other functions than mere y to guide the counterbore cutting edges.

For a more complete understanding of this invention reference may behadtothe accon panying drawings in whiblk Figure 1 is a side elevation-oi. a counterbore constructed according to this invention.

Figure 2 is'a side elevation of the' end portion thereof, the pilotliaving been re moved:

Figure 3 is a section on line 3-3 of Figure 2'.

Figure 4 member.

Figure 5 is a section on line 5'-5 ofFigure 4:.

Figure 6 shows thepilot made in the form of a' drill".

Figure? shows the pilot adjusted to form a depth gageforthe counterbore'.

Figure 8 shows a pilot of relatively'l'arge diameter, the counterbored hole beingdiagonal to the surface of the work.

Figure 9 shows the pilot extended to bear within thehole when the counterbored' per.- tion has been cored out.

Figure 10 shows the pilot formed as a rose reamer.

Figure 11 is a side elevation showing a four bladed counterbore.

Figure 12 is a'section on line 12 12 of Figure 11;

Figure 13 shows a modified construction particularly designed forcutting tube holes in boiler tube sheets.

Referring first to Figures 1 to 5, 1 indicates a blademember-having cutting edges 2 formed at one end and a shank- 3 of any suitable form for engagement with driving mechanism at the other. Intermediate the side edges of the blade portion 2a channel 4: is. formed longitudinally on each side thereof and centrally of this channel a slot 5 is cut through this piece.

The pilot member comprises a cylindrical end portion 6 having a shank 7 extending therefrom slotted out to form a pair of spaced jaws 8, the space 9' therebetween being of sufficient width so that the jaws 8 may engage opposite sides of the blade member sliding within the opposed clannels 4: on opposite sides thereof. Adjacent. to their ends the jaws 8 are perforated, at lO is a side elevation of the pilot for the reception of a tighteningbolt 11 which may extend through the slot 5 and when tightened. clamps the jaws 8 firmlyto the blade member 1 with the cylindrical portion 6 extending beyond the cutting edges 2 as shown in Figure 1. A plurality of pilot members having cylindrical portions 6 of dili'erent diameters may be employed with each blade member 1, the jaws 8 in all these forms being of such size as to fit within the channels 4.

hen it is desired to sharpen the cutting edges 2 the pilot member is removed, whereupon the grinding tool may act on the entire cutting edge which is left freefrom obstruction as will be evident from an inspection of Figure 2. The pilot member may then be assembled with the blade member, the jaws 3 being clamped in position in the channels 1 within which they fit sufiiciently closely so that the pilot portion 6 is in correct axial alinement with the blade portion. By means of the tightening bolt 11 passing through the slot 5 the distance to which the pilot portion 6 extends beyond the cutting edges 2 may be adjusted as may be desired. F or example, it may be adjusted to form a depth gage to determine the depth of the counterbore as is illustrated in Figure 7 in which the pilot portion 6 passes entirely through the work when the counterbore cutting edges 2 have reached their proper depth from the upper face of the work.

The pilot portion 6 may also be extended so that it bears firmly within the guiding hole 21 of work in which the counterbore portion has been cored out as shown in Figure 9 so that the pilot may have bearing within the hole 21 before the cutting edges 2 have begun to act on the work. By this means proper positioning of the counter-e bored hole is insured even though the counterbored portion may be so deep as to make it impossible for the pilot as ordinarily constructed to reach the guiding hole with which the counterbore is desired to be in axial alinement before the edges 2 are brought into action.

In Figure 8 the pilot portion 26 is shown as of a larger diameter than the pilot portion 6 of Figures 1, 4 7 and 9, this illustrating diiferent proportions of counterbored diameter and pilot hole diameter which may be effected by the construction of this invention. This figure also illustrates the manner in which the pilot portion 26 is properly guided within its guide hole diagonally to the face of the work.

In Figures 6 and 10 the pilot is shown a cutting tool instead of merely as a guide member, in Figure 6 this pilot portion 28 being formed as a bit to bore its own hole in the work and in Figure 10 the pilot portion 29 being formed as a rose reamer to enlarge the hole within which it is guided.

In Figures 11 and 12 is shown a construction in which the blade member is provided with four blades each having a cutting edge at its end. These four blades are indicated at 30. In this construction the pilot member has a pilot portion 31 and spaced jaws 32 which engage within the opposite angles between pairs of blades 30, the jaws being. held in clamped position by means of a clamping bolt 33 extending through a slot 34 through the blade member.

Still another embodiment of this invention is the special tool shown in Figure 13, particularly intended for cutting tube holes in boiler tube sheets. As therein shown the guiding pilot portion 35 of the pilot mem ber is of comparatively small diameter, the jaws 36 being much larger and fitting within correspondingly wide channels in the blade member 37. This blade member is extended to form cutting edges 38, intermediate these edges the blade member is cut away as shown. by the dotted line at 39. Each cutting edge 38 is therefore considerably narrower than the distance between its outside diameter and that of the pilot portion 35. p This pilot portion engages within a pilot hole formed within the boiler tube sheet and the blades 38 cut in an annular path coaxial with the pilot 35 through the boiler sheet, thus leaving a central uncut ring or washer portion 39 which drops out. This avoids the necessity of cutting away the entire mass of metal within the desired diameter of the hole for the boiler tube, this representing a material saving in power required to cut the tube holes.

Having thus described certain embodiments of this invention it should be evident to those skilled in the art that various changes and modifications might be made therein without departing from its spirit or scope as defined by the appended claims.

I claim:

1. A device of the class described comprising a blade member having end cutting edges and longitudinally slotted back of said edges, a pilot member slotted from one end to form a pair of jaws to take over said blade member, and means engaging the free ends of said jaws and passing through the slot of said blade member to clamp said pilot member to said blade member in adjustable axial relation.

2. A device of the class described comprising a blade member having axially arranged channels on opposite faces and cutting edges at one end, a pilot member having spaced jaws engaging in said channels and projecting beyond said cutting edges, and means for fixing said jaws in said channels.

3. A device of the class described comprising a blade member having axially arranged channels on opposite faces and slot- 5 ted through a portion of its length within said channels, a pilot member having a substantially cylindrical head at one end and slotted to form a pair of opposed jaws fi.t ting within said channels, and a clamping bolt passing through perforations adjacent a pilot member having a pilot portion at 10 to the free ends of said jaws and through one end and a pair of jaws at the opposite said slot for fixing said pilot member to end formed to engage in said channels, said said blade member in longitudinally adjustpilot and jaw portions being of different able substantially coaxial relation. diameters, and means for fixing said jaws 4. A devlce of the class described coinin position. prlslng a blade member having axially ar- In testunony whereof I have afiixed my ranged channels on opposite faces and cutsignature. ting edges at one end of said blade member, ALLEN C. DE ROCHEMONT. [11. s.] 

